How to Flash Custom ROM on Android

Flashing a custom ROM on Android is like an emerging trend these day, that helps users to expand their experience over this powerful and amazing platform. I have been using custom ROMs ever since I bought my first Android (during 2011) when TWRP didn’t even see the day-light. I remember banging my head, reading several threads for my device, on how to flash custom ROM. It seems like a child’s play now, but back then, even when I was a noob, things were messy.

The same way, I believe, we get thousands of new Android users who join the Android custom team, of which for most of the general crowd, flashing a custom ROM is a blunder and a totally new concept. If you are one of them, don’t feel sad about it at all. As they say – “We are imperfect in ways that we can’t see“.

We are going to help you on how to flash custom ROMs on your Android. Irrespective of the manufacturer or version, flashing custom ROMs follow the same procedure overall. We will take TWRP into consideration, which is a major custom recovery available, and everyone seems to use it.

If you still haven’t chosen a custom ROM, you can find one for your device at XDA-Developers forum. And once you have, the next thing you will need is TWRP installed on your Android, you can search for your device specific guide here.

I have a Nexus 6P, and I am going to use Chroma ROM for demonstration. Now without any delay, lets head over to the instructions.

How to Flash Custom ROM

Its easy, flashing a custom ROM via TWRP and could be done within a matter of minutes.

STEP 1: First, download what you are going to flash – a custom ROM zip and GApps zip. GApps are provided separately at most instances, but some known ROMs like Cataclysm include them by-default. In my own case, GApps have to be flashed seperately and I have grabbed them from OpenGApps.org.

STEP 2: Now, it is necessary to transfer your ROM and GApps zip files to your device’s storage, until and unless you are going to sideload your ROM. So, connect your phone or tablet to the PC via USB cable, in MTP or USB Storage mode, which ever is available and supported.

STEP 3: Its time to boot into recovery mode, and we all tend to do this by pressing the hardware-key combination meant for our device. For in my case, with the Nexus 6P, it could be done by pressing the Volume Down and Power key to enter bootloader and finally selecting Recovery mode from there. If you don’t know the right combo for your device, you can always use the following command in CMD or Terminal window, making sure that your phone is connected to the PC and has USB debugging enabled.

adb reboot recovery

STEP 4: Once the device has booted into TWRP recovery mode, you will see the main screen with several options (See the image below).

We will first wipe the current ROM completely. How? By wiping some specific partitions. Go to Wipe > Advanced Wipe. Now, select the following check-boxes:

Dalvik/ART Cache

System

Data

Cache

You will see “Swipe to Wipe” on the bottom of the screen, just swipe the button. It will take a few seconds to complete, and after that, just go back to the main TWRP screen.

STEP 5:Time for ROM installation now! Pretty simple, just tap on Install. Browse your internal/external storage and navigate to the location where you have copied the zip files in step #2. First, tap on the ROM zip file (e.g. chroma_angler-2016-02-03.zip), and once it has been selected, you will add the GApps to the flashing queue. To do so, tap on Add more Zips. Again, navigate and select the GApps zip file (e.g. open_gapps-arm64-6.0-mini-20160206.zip) now.

If, in case there are additional mods or essential zips that are needed to be flashed, follow the same method as that of GApps, to add the required flash-able zip(s) to the queue.

When both the files have been selected and added successfully to the flash queue, you can swipe the “Swipe to confirm Flash” button. Flashing procedure may take a few minutes, depending upon the size of the ROM, and the number of files. When its done, you can tap on Reboot System.

Your phone will now reboot into the custom ROM that you chose for your device. The first boot may take a few minutes, or even some more time depending upon the size of the custom ROM. So, we have guided you on how you can easily flash custom ROMs on your Android smartphone or tablet. If you feel yourself stuck anywhere, during or even after the process, you can comment below and ask us.

Dhananjay (DJ) is an Android devotee and a Tech Blogger by profession. He is a keen undergraduate, seeking and working hard on his ambitions to achieve something distinctive in his life. He prefers interacting with his readers in the most reproaching manner possible and his desires here are not just to reach out the tech figures, but also attract those non-interested minds to our Android universe. He proudly owns Nexus 6P, Nexus 5, OnePlus One and a Nexus 4.

How long does it take to reboot after flashing with chroma rom? mine seems to have been stuck at Google logo for over 30 minutes. I have followed the instructions and both the rom and gapps installed successfully but rebooting to android is not happening

Hello Kamal, which device are you on? Also, are you sure that you flashed the correct ROM and GApps?

Kamal Chowdhury

Hi Dhananjay, thanks for your prompt response. I am on Nexus 6P. Tried the procedure exactly in the way you described. Flashed Chroma with stock GApps downloaded from the link you provided. Both installed without showing any error but the booting stuck at android logo for more than 30 minutes. Later on I had to install purenexus rom and did it successfully without a hiccup. I wanted to solve the radio band problem as my device is not showing any network signal despite trying different sims. It was on android 7.1.2 when the problem started. Unfortunately, flashing pure nexus rom didn’t solve the problem. I read somewhere Chroma rom fix the radio band problem that why I wanted to flash chroma. It’s my bad luck. I bought my phone from USA and i can’t get back there just to claim the warranty service. SO I guess I now have a dead phone which will work as a tablet rather than a phone.

I would say that you should stick to PureNexus ROM on your 6P. Chroma is no longer maintained by the developer.

As for the radio issue, is your 6P a carrier based device? What I mean is, that is it a GSM variant or a carrier-based device like Verizon, T-Mo, etc?

Also, what version of TWRP have you got installed?

Kamal Chowdhury

Sorry to get back to you late. My nexus 6P is unlocked GSM version not dependent on any particular carrier. While I was in USA i used TMobile sim and when I came back to my country I had no problem using the local GSM based carrier for the last one year. Purenexus rom also failed to bring back the radio signal and the phone is unable to connect to any network. I installed twrp 3.1.0-0 angler version. Do you think the radio band which i found turned off, is a hardware issue rather than a software one? In that case I will have to take it to the repair shop. if not do you think installing chroma might solve? I heard that chroma fixed the radio band issue.

Dear Dhananjay, Can you help me a little bit more? just a hint about how to restore efs backup. A simple instruction would be really helpful as I am not an expert in flashing/rooting. I have downloaded the backup file from the google drive link you provided and copied the file into the phone’s internal storage. Looking forward to hearing from you

Okay, so will start by booting into TWRP. Now in TWRP, tap on the “Restore” tab. In there, you shall automatically see the file to restore. So you just have to tap on the file and follow the on-screen instructions to restore it.

Note that the folder I provided must be inside the TWRP folder, or it will not detect the backup file.

Kamal Chowdhury

Just started restoring it. (actually your last line solved as I was unable to find the back up file.) Just crossing my finger that it will give me back my phone. Thanks a bunch for the awesome support. I wish I could do something for you as well.

Only if you want to do something, kindly share our website with your friends. We would love to be known by as many Android users as possible. You can also contribute to use by tipping us articles. 🙂

Kamal Chowdhury

So sorry to let you know. It didn’t solve the issue. Even after succesful efs restore there’s still no network signal. trying to search network returned with error message. I am feeling kind of heartbroken as it was my last attempt after trying so many things. I guess I kind of let you down also.

Can you share the link to the latest radio? my device showing baseband version angler 03.72. I have done complete factory image to android 7.0 but it didn’t help. Later I flashed to Purenexus which didn’t solve also. By the way is it okay to flash only the radio?

You need to flash this using the following command:
fastboot flash radio radio-angler-angler-03.81.img

Kamal Chowdhury

Well I am on it. Now there’s an option in twrp recovery: ” Select partition to flash image: Boot, System Image, Vendor image, Recovery. Which one shall i choose? also do i need to wipe the previous radio image before flashing the new one?

The radio image is supposed to be flashed in bootloader mode, and not in recovery. So, boot your phone into the bootloader mode, connect it the PC, and flash the radio by entering the following command in CMD/Command Prompt:
fastboot flash radio radio-angler-angler-03.81.img

Kamal Chowdhury

I flashed the new radio image successfully but it’s still the same. ” No Service”. Sorry again.

I dearly hope that it is not a hardware issue. In the first screenshot, do you see Cellular Radio Power option? It should be enabled.

Kamal Chowdhury

Dear Dhananjay, I enabled the cellular radio. It did not work. Also I have been searching threads on this and now getting information that it may not be a hardware issue. Some People who enrolled in Android beta and installed nougat 7.1.2 are facing this issue. I found two other person from my country who are facing the same issue since last week. A Google rep also commented that the phone might work in USA or Europe. This whole thing is getting messed up. If you have time please read the comments from this link. Might help you to give an idea about what’s going on. https://support.google.com/nexus/forum/AAAANseOu18Nx3zxCAHsCU/?hl=en

I am sorry to hear that. But have you also tried switching to a different SIM card or changing the “Preferred Network Type” that is shown in the first screenshot? If it still doesn’t work, I believe the last resort is to take the device to the RMA for repair. You can consult them for the charges before hand.

Kamal Chowdhury

Hi Dhananjay, I have decided to unroot my nexus 6P and get back to stock. Heard some people solved their problem using the February stock image from Google (N4F260). I will give it a shot and see if my luck opens up. Can you share any link where I can get the information on how to un root nexus 6P and get back to stock image without bricking the device? That would be really helpful

Hi, so you can simply restore everything back by flashing the factory image. I recommend a full factory image flash, that will erase your device’s internal storage too. So make sure that you take a backup first.